Corticosteroid injections form a significant part of the injectable
therapy arsenal that sports & exercise medicine physicians use to
treat musculoskeletal injuries.
At the recent ISEH Masterclass in April 2016, ISEH Consultant in Sport & Exercise Medicine Dr Rick Seah presented on the topic of ‘Injection therapies’ and the current
trends and research findings.
Here is a distillation of part of his presentation, focusing primarily on Corticosteroid injections - Then & Now.
Introduction
Corticosteroid injections form a significant part of the injectable therapy arsenal that sports & exercise medicine physicians use to treat musculoskeletal injuries. Indications for their use may include pain, swelling and stiffness.
A brief history
The historical basis of injections is as follows- Joint aspiration was formally described in the medical literature in the 1930s. Intra-articular corticosteroid injections (with hydrocortisone acetate) dates back to 1951 by Dr Joseph Hollander and his colleagues. This involved a case series of 1,300 patients and over 17,000 hydrocortisone injections to various joints, bursae and tendon sheaths over a period of 4 years! 1,2
Things have certainly changed since that time. Up to 15 years ago, it was mostly corticosteroids that were injected for most musculoskeletal conditions, essentially making it ‘the tool for every job’. This worked well for some conditions but was sometimes associated with side effects, especially if a patient was given repeat corticosteroid injections in quick succession.
Side effects are generally uncommon but can include localised skin pigmentation changes, lipoatrophy, calcification around the joint, allergic reaction to the constituents, tendon rupture, infection and systemic side effects. The most common side effect to occur is a ‘steroid flare’, thought to affect up to 1 in 20 patients injected. This is an acute exacerbation of pain within 1-2 days of having the injections. It generally subsides quickly with a combination of rest, ice and oral anti-inflammatory medication (NSAIDs).
There is now a greater awareness of other injection options such as Viscosupplementation (with hyaluronic acid injections), Prolotherapy (also known as sclerosant injections) for treating ligamentous laxity and Orthobiologic therapy (such as autologous blood and platelet-rich plasma injections) for tissues that have poor healing properties.
There is also a greater emphasis on the multi-disciplinary team (MDT) approach, rehabilitation and prevention. Injections alone, without counselling or referral for appropriate post-injection rehabilitation to physiotherapy and allied health colleagues, may be associated with poorer clinical outcomes.
Indications
The following anatomical structures can be injected- joints, tendon sheaths, ligaments, muscles, musculotendinous junctions and the intermuscular plane. In the spine, the following areas can be injected- epidural space (epidural injections), facets (facet joint injections) and intraforaminal spaces (nerve root injections).
There are some areas where corticosteroid injections should be avoided, such as directly into tendons, nerves or vascular structures. Increasingly, there is a move away from injecting corticosteroids for tendinopathy (e.g. Achilles tendinopathy) as these conditions are primarily degenerative in nature, not inflammatory. These is also a concern about repeated injections increasing the risk of a tendon rupture.
The clinical conditions for having a corticosteroid injection are wide ranging. Examples include carpel tunnel syndrome, De Quervain’s tenosynovitis, osteoarthritis, gout and rheumatoid arthritis. In the spine, examples include degenerative disc disease, facet joint arthritis and nerve root entrapment.
Public perception
It is worth noting that corticosteroids (which this article refers to) and anabolic steroids (which are used illegally as an ergogenic aid to stimulate muscle mass and therefore banned by anti-doping authorities) are not the same. Thankfully, this misconception occurs less often now as patients are able to access medical information more readily from the Internet and are therefore more discerning.
Our role as health professionals enables us to clear up such misconceptions by way of disseminating health information and having open discussions with patients beforehand. It also provides us with a public health opportunity to discourage those patients who may be contemplating or are already using anabolic steroids. Some online resources are readily available to help us reinforce this message (e.g. www.talktofrank.com)
Mechanisms of action
Corticosteroids have a multi-modal mechanism of action, working in many ways. These include rreduction of the inflammatory reaction (by limiting capillary dilatation & vascular permeability); restricting accumulation of leucocytes and macrophages; reduction in the release of vasoactive kinins and inhibition of the enzymes that can destroy normal tissue indiscriminately.
Additionally, new research suggests corticosteroids may inhibit release of arachidonic acid from phospholipids, reducing formation of prostaglandins which are known to cause pain. Importantly, clinicians should appreciate the act of introducing a needle to injured tissue may in itself provide drainage and release of pressure. It may also mechanically disrupt scar tissue in muscle. (Medscape website)
Do corticosteroid injections work?
In everyday clinical practice- yes, they do. Clinicians are able to see for themselves that patients once crippled with pain are often visibly much improved and able to get back to activities of daily living and normal physical activities.
The evidence base is less convincing for its efficacy. Possible reasons for this dichotomy may include comparisons between heterogeneous patient populations. It is acknowledged that patients may feel so well after corticosteroid injection that they neglect to do the rehabilitation exercises and address the underlying reasons (e.g. poor posture, overuse, poor technique, inadequate recovery periods) that caused the issue to present in the first place.
What do corticosteroid injections consist of?
Corticosteroid injections commonly consist of the following: A corticosteroid (e.g. methylprednisolone/ triamcinolone acetonide/ hydrocortisone) and a local anaesthetic (e.g. short-acting lidocaine or long-acting bupivacaine). The local anaesthetic component may be injected subcutaneously first to decrease pain for the patient.
Practical tips
General principles
In general, a big joint such as the hip or shoulder will require a bigger volume of fluid and bigger/ longer needles. A smaller joint such as the acromioclavicular or interphalangeal joint will require a smaller volume of fluid and a smaller/ shorter needle.
Carrying out an intra-articular injection (where you inject into a joint) requires a ‘bolus technique’. Carrying out a soft tissue or peri-articular injection (whereby you are not injecting into a joint) can employ either a bolus or peppering technique, depending on the clinical scenario and tissue injected.
Avoid the use of local anaesthetic containing adrenaline when injecting into extremities such as the fingers and toes due to the risk of severe vasoconstriction and subsequent digital ischaemia.
Be PRACtical!
An aide memoire can be helpful to ensure a meticulous approach to carrying out these injections.
(PRAC: Procedure, Risks, Aftercare, Consent)
Procedure and the indications for doing the injection are explained to the patient.
Risks that can be associated with the injection are also explained.
Aftercare instructions and information on what to expect is given.
Consent from the patient is obtained and documented. Signed written consent is preferred, but informed verbal consent is also acceptable, provided this is accompanied by meticulous data entry into the patient’s clinical notes.
Keep it clean!
Sterility is vital to minimise the risk of infection. Take time to clean and prepare the area thoroughly. Employ a ‘No touch’ injection technique.
Aim to keep the patient around for at least 15min after injection (either in a seated or supine position) to observe for delayed reactions such as a vasovagal episode, mild allergy or anaphylactic shock.
Take home messages
- Corticosteroid injections reduce pain and inflammation. They permit a ‘window of opportunity’ to progress rehabilitation but importantly, they are not a cure. It is vital that patients are aware of this as part of reasonably managing their expectations.
- There is an increasing expectation to do these injections under imaging guidance (e.g. ultrasound, x-ray or CT-guided) for accuracy. Although this would seem logical, the evidence base provides food for thought with some research papers demonstrating that in certain conditions, non-guided injections, based on a good knowledge of anatomical landmarks, can give equally promising results. 3, 4
- Timing of these injections is important. Many acute injuries will settle with time and may not require these injections.
- Even if the corticosteroid injection does its job well, if the underlying cause is not addressed and remedied, the problem is likely to recur.
Selected references
1. Hollander JL et al. Hydrocortisone and cortisone injected into arthritic joints. Comparative effects of and use of hydrocortisone as a local antiarthritic agent. JAMA 1951;147:1629.
2. Hollander JL et al. Local Anti-Rheumatic Effectiveness of Higher Esters and Analogues of Hydrocortisone . Annals of the Rheumatic Diseases. 1954;13(4) 297-301.
3. Bloom JE et al. Image-guided versus blind glucocorticoid injection for shoulder pain. Cochrane Database of Systematic Reviews 2012, Issue 8.
4. Mahadevan D et al. Corticosteroid injection for Morton’s neuroma with or without ultrasound guidance. Bone Joint J. Apr 2016, 98-B (4) 498-503.